Touch Up Paint

Can anyone please help me get hold of the paint code , so I can get a touch up aerosol for the white side panel on a Autotrail Chieftain . I contacted Autotrail but the code the gave me does'nt come up on any paint suppliers range . The code they gave me is 5XCI . Could it be that its the same as the Fiat panels , though it does seem a little darker on the side panels . suppose the last resort is to take the Van to a paint supplier and get them to match it .